ASVAB Mechanical Comprehension Practice Test 111380 Results

Your Results Global Average
Questions 5 5
Correct 0 2.92
Score 0% 58%

Review

1

What is work?

60% Answer Correctly

Force per unit distance

Force per unit time

The movement of an object by a force

The potential for exertion
Solution

Work is accomplished when force is applied to an object: W = Fd where F is force in newtons (N) and d is distance in meters (m). Thus, the more force that must be applied to move an object, the more work is done and the farther an object is moved by exerting force, the more work is done. By definition, work is the displacement of an object resulting from applied force.

2 What is the efficiency of a machine has work input of 70 ft⋅lb and work output of 45 ft⋅lb?
67% Answer Correctly
65%
1%
32%
130%
Solution
Due to friction, a machine will never be able to utilize 100% of its work input. A certain percentage of that input will be lost in overcoming friction within the machine. Effeciency is a measure of how much of a machine's work input can be turned into useful work output and is calculated by dividing work output by work input and multiplying the result by 100:
\( Efficiency = \frac{Work_{out}}{Work_{in}} \times 100 \) \( = \frac{45 ft⋅lb}{70 ft⋅lb} \times 100 \) \( = 65% \) %
3 If the handles of a wheelbarrow are 1.0 ft. from the wheel axle and the load is concentrated at a point 1.0 ft. from the axle, how many pounds of load will a 170 lbs. force lift?
47% Answer Correctly
334.2
0
82
170
Solution
This problem describes a second-class lever and, for a second class lever, the effort force multiplied by the effort distance equals the resistance force multipied by the resistance distance: Fede = Frdr. In this problem we're looking for resistance force:
\( F_r = \frac{F_e d_e}{d_r} \)
\( F_r = \frac{170 \times 1.0}{1.0} \)
\( F_r = \frac{170.0}{1.0} \)
\( F_r = 170 \)
4

What's the first gear in a gear train called?

57% Answer Correctly

driver gear

input gear

driven gear

idler gear
Solution

A gear train is two or more gears linked together. Gear trains are designed to increase or reduce the speed or torque outpout of a rotating system or change the direction of its output. The first gear in the chain is called the driver and the last gear in the chain the driven gear with the gears between them called idler gears.

5

The mechanical advantage of a wheel and axle is equal to the:

61% Answer Correctly

length of the axle

difference in the diameters of the wheels

difference in the lengths of the axles

ratio of the diameters of the wheels
Solution

A wheel and axle uses two different diameter wheels mounted to a connecting axle. Force is applied to the larger wheel and large movements of this wheel result in small movements in the smaller wheel. Because a larger movement distance is being translated to a smaller distance, force is increased with a mechanical advantage equal to the ratio of the diameters of the wheels. An example of a wheel and axle is the steering wheel of a car.